Vessel occlusive devices are well known and commonly referred to as “artificial Sphincters”. They are installed within the body to aid or replace the natural sphincter of the body. For example, men become urinary incontinent following surgeries to remove cancerous prostates. Women are often rendered incontinent due to the pelvic trauma caused during childbirth and due to a laxity of the pelvic muscles occurring due to aging. To a lesser degree, men and women may be rendered incontinent due to trauma, infection and birth defects. Urethral occlusive devices can be used to restore urinary continence to patients with urinary control problems caused by various neurological diseases, surgical procedures, spinal cord injury, etc. Other occlusive devices include those used for contracting the bowel to prevent fecal leakage, for contracting the esophagus to prevent gastro-esophageal reflux, or those used in the area of gastric banding for restricting the stomach in treatment for obesity, and occlusion of the seminal vesicles or fallopian tube to control male and/or female fertility, of which there are needs that exist for commercial devices that can be used in such applications.
In particular, devices utilizing hydraulic sphincters or cuffs described in U.S. Pat. Nos. 3,863,622; 4,222,377, 4,412,530 and 4,878,889, have been used to provide urethral occlusion. To use these types of devices, the patient squeezes a control pump, which transfers fluid from a cuff to a pressure regulating balloon. The balloon forces the fluid through a fluid restrictor and back into the cuff to reestablish an occlusive urethral pressure within 3-5 minutes. These urethral occlusive devices are complicated to implant. One problem with hydraulic sphincters or cuffs is that they often do not apply uniform pressure on the urethra. As the cuff or sphincter is inflated, it folds or changes its shape, often in a non-uniform manner, thereby exerting uneven occlusive force on the urethra. This can result in urinary leakage, urethral erosion, or the urethra tissue being worn away after extensive use.
In other examples, the American Medical Systems, Inc. AUS 800 is a commercially available, totally implantable artificial urinary sphincter. The complexity of its implantation is due to the requirement to intra-operatively fill and assemble its three components. The AUS 800 often fails due to wear in its componentry which leads to fluid leakage. Urethral atrophy and erosion sometimes occur and are suspected to be due to the crenate shape of its occlusive cuff. Post-operative infection requiring explantation of the device also is a frequent complication.
U.S. Pat. Nos. 5,704,893 and 6,074,341 discuss other types of urethral occlusive devices, which are entirely implantable artificial urinary sphincters. These artificial urinary sphincters are one-piece devices that do not require saline filling or intra-operative assembly, but where depression of a deactivation plunger, for example through the scrotal skin, causes a urethral occlusive sheath to expand and remove occlusive pressure from the urethra to allow normal urination. Depression of an activation button allows the occlusive sheath to contract and reapply urethral pressure to prevent urethral leakage. While such devices provided significant improvement in vessel occlusion, implantation in humans was impeded by growth of tough, fibrous tissue around the device, due to the natural defenses of the human body, which over time prevented expansion of the occlusive sheath.
For these and other reasons, there is a need to provide a practical and effective vessel occlusive device for aiding or replacing the natural sphincter of the body.